In the past various means have been used to control the tension of yarn or thread on textile equipment. These means have included disc-shaped members with the yarn running therebetween, various other pressure friction means, and more recently cup-like members generally made of plastic or similar material with the yarn passing axially therethrough and being tensioned by a metal ball bearing-like member contained within the cup. Tensioning devices of this type are simple and yet highly efficient with the tension being variable by varying the size and weight of the balls.
Wear is always a problem in tensioning means. Ceramic inserts in the bottom of the cup and in the center of the cover or lid used in conjunction therewith eliminated the excessive wear problem but not the excessive build-up of wax and lint due to the magnetic attraction of static electricity created by the fast moving yarn through the device.
Also the brackets that mounted the prior art tension means very quickly warp under the heat and vibration of operation so that the device is no longer aligned with the yarn. When this happens, either excessive tension or inadequate tension is encountered. Since the entire textile machine in many instances must be shut down to replace the tension devices used therewith, they are allowed to continue to run even though they are twisted or distorted to a point of near uselessness. This, of course, can very quickly affect the quality of the product being manufactured as well as creating expensive down-time for the equipment.
Further, during the threading of the yarn through the prior known tensioning devices, the cap is removed therefrom so that a threading wire can be run therethrough. Because of the large number of tensioning devices that must be threaded, the operator very often in his haste will knock the tension ball or bearing out of the cup and the same will roll across the floor of the plant creating an under-foot hazard as well as being not readily retrievable. The entire threading process must then be stopped until the ball can be replaced in the cup. Additionally, the operator will quite often leave the cap off of the cup, particularly if the same has become distorted due to heat or other causes and does not fit properly. During later operation of the machine, the jerking of the yarn will cause the ball to be thrown from the cup thus again creating an under-foot hazard as well as rendering the tension means completely useless.